Normal Operation of JFET: Identify the region of operation in which a Junction Field Effect Transistor (JFET) functions under normal amplifier conditions.

Difficulty: Easy

Correct Answer: constant current region

Explanation:


Introduction / Context:
JFETs are voltage-controlled devices widely used for amplifiers. Their operation is divided into cutoff, ohmic, saturation (also called constant current) regions. Amplification occurs only in a particular region.



Given Data / Assumptions:

  • Device: JFET.
  • Regions under consideration: constant voltage (ohmic), constant current (saturation), cutoff.


Concept / Approach:

For amplifier action, the device must have drain current controlled primarily by VGS, not by VDS. This is the saturation region, also referred to as the 'constant current region.'



Step-by-Step Solution:

Cutoff: ID ≈ 0, no amplification.Ohmic (constant voltage): behaves as resistor.Saturation (constant current): ID ≈ f(VGS), suitable for amplification.


Verification / Alternative check:

Amplifier bias points are always chosen in constant current region for linearity.



Why Other Options Are Wrong:

  • Constant voltage: only resistive operation.
  • Both: misleading, only constant current correct.
  • Cutoff: device off.


Common Pitfalls:

  • Confusing ohmic and active regions.


Final Answer:

constant current region

Discussion & Comments

No comments yet. Be the first to comment!
Join Discussion